随着农业生产经营形式的变化和生产、收获及贮藏等条件的限制,农作物良种混杂退化的问题也日趋严重.不少优良品种,七八年才培育出来.但一进入大田,三四年工夫就丧失了良种的种性.不少科技人员呼吁.当前良种推广出现了“短、低、差”现象,即良种使用年限短了,种子纯度低了,经济 With the changes in the form of agricultural production and production, harvesting and storage and other conditions, the aggravating problem of agronomist crops aggravate, many elite varieties were cultivated only in 1978 and 1988. However, A lot of scientific and technological personnel called for the current promotion of the emergence of “short, low, poor ” phenomenon, that is, the use of fine varieties of short life, low purity seeds, the economy